It is currently conventional to utilize LCD and LED displays in an almost infinite variety of applications to present information in numeric form. This is particularly true with respect to instrumentation of virtually all types. Such planar displays are inherently two dimensional.
Prior to the advent of planar solid state displays, such as LCD and LED by way of example, it was long the practice to present numeric information in instrumentation through the use of mechanical counter wheels or drums such as found for example in Veeder-Root counters of the type utilized in automobile odometers, engine hour meters and the like. While these displays may popularly be perceived to be two dimensional, they are in fact three dimensional by virtue of their use of cylindrical wheels or drums. With such an arrangement the figures on the wheels can be seen advancing in the instrument display window in one direction or the other. As a result the viewer can perceive a trend in the direction of the readout either up or down. Instrumentation of this type is common in automobiles, aircraft, boats, etc.